Improvement in furnaces for annealing plowshares



w. M. WATSON'.

|mproverr'i'ff i Furnaces for Annealing Plews'hares, etc.

N0, 123,528, Patented Feb. 6, 1872.

l nl" WILLIAM MEDI) WATSON, OF TONIOA, ILLINOIS.

IMPROVEMENT IN FURNACES FOR ANNEALING PLOWSHARES, &c.

Specification forming part of Lctters'Patent N 123,528, datcd February 6, 1872.

To all whom it may concern:

Be it' known that I, WiLLIimr M. WATSON, ofTonica, in the county of La- Salle and State of Illinois, have invented a new and valuable Improvement in Furnacesf7 and I do hereby declare that the following is a full, clear, and exact description of the construction and operation ofthe same, reference being had to the annexed drawing making a part of this specification, and to the letters and figures or reference marked thereon.

Figure I of the drawing is a representation of a top view of my furnace. Fig. 2 is a central vertical section ofthe saine.

My invention has relation to means for tempei-in g plow-plates and other irregular bodies and it consists in the construction and novel arrangement of the process hereinafter particularly described.

The letter A of the drawing designates the oven-chamber. This chamber is surrounded with the double walls B B on all sides, and is divided from the chamber' O below by the horizontal part-itioii or tloor D. Between the walls B B is a space, E, which is designed to receive a iilliiig, F, of ashes or other non-conducting substance. G represents a circular recess formed in the floor D of the oven, and designed to receive the circular rotating hearth I-I, whose upper surface is made liush with the surface of the tloor D. K represents the shaft of the rotatiii g hearth, passing vertically down through the center of the oven-Hoor and provided at its lower end with a belt-wheel L in the chamber O. M M are the hot-draught passages, one of which leads to the smoke-stack and the other to the lire direct. 'mm represent the dainpers which regulate the draught through these passages. N N represent the side or cold-air passages, and n a their regula-ting-dampers.

Having thus described the different parts of my temperingoven, I will now explain the inode of operation. It is an exceedingly diflcult and delicate matter to heat any large irregular metallic body in a uniform manner; and if this is not done in the tempering operation the metal will be hard in some places and soft in others. Let us suppose that the metallic parts of a plow are lto be tempered. They are usually first set up-t-hat is, the moldboard, share, and land-side are bolted to the standard. Then they are placed ou the hearth, which is made to revolve, the tire and smoke passages being open and the cold-air passages closed. Thus all sides are brought in contact with the heat, and the effect is usually to heat them alike. But should one part heat faster than another, the heat from the tireis shut off by closing the damper, a-nd the smoke-passage is also closed, while the hearth continues to revolve until all the parts are of a uniform heat. If the parts are too hot the side dampers are opened until they are sufficiently cooled. Then the proper degree of heat is attained the plow should be withdrawn from the oven and cooled in water or some tempering mixture.

The hearth is nsuall5v formed of a circular plate of cast-iron supported on an upright shaft and provided with a layer of fire-brick on its upper surface of sufficient thickness to hold the heat and prevent warping of the plate. The inner wall B is laid of lire-brick and the outer wall of common brick, the space between being iilled with dry ashes, the object of which is to allow the inner brick t0 expand and contract without danger of cracking the outer wall, and also to hold the heat. y

What I claim as my invention, and desire to secure by Letters Patent, is

The process herein described for tempering plowshai'es and other irregularly-shaped metallic bodies with uniformity bythe means substantially as speciied.

In testimony that I claim the above I have hereunto subscribed my naine in the presence of two witnesses.

IVILLIAM MEDI) WATSON.

Witnesses:

HENRY GUNN, J om: MORRISON. 

